Metal oxide thin-film transistor and manufacturing method for the same

ABSTRACT

The present invention relates to a metal oxide thin-film transistor and manufacturing for the same. The thin-film transistor includes a substrate; a source electrode, a barrier layer and a drain electrode which are sequentially formed on the substrate; and a semiconductor active layer formed on side surfaces of the source electrode and the drain electrode; wherein, the semiconductor active layer is respectively connected with the source electrode and the drain electrode. The metal oxide thin-film transistor has a new structure, wherein the source and drain electrodes are parallel to the substrate, and the semiconductor active layer is contacted with the source electrode and the drain electrode by a vertical covering or a step covering way. The channel length does not depend on the photolithography process, but depends on the side length of the source and drain electrodes contacted with the semiconductor active layer.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a wafer manufacturing field and adisplay technology field, and more particularly to a metal oxidethin-film transistor and a manufacturing method for the same.

2. Description of Related Art

In recent years, along with the increasing size of the liquid crystaldisplay, a frequency of a driving circuit is continuously increased. Themobility of the conventional amorphous thin-film transistor is hard tomeet the requirement is that a thin-film transistor having highermobility has become a hot topic for companies and research anddevelopment staff. The thin-film transistor having high mobilityincludes a polysilicon thin film transistor and a metal oxide thin-filmtransistor. Wherein, although the polysilicon thin film transistor has ahigher mobility, but the uniformity is poor and the manufacturingprocess is complicated so that the cost is higher and the productivityis lower. In comparison, the metal oxide thin-film transistor has a highmobility and uniformity are the same time, and a relative lowmanufacturing cost such that the metal oxide thin-film transistor isregarded as a key technology of a next flat display.

Along with the improvement of the performance of the display, thethin-film transistor requires a shorter channel. Because the thin-filmtransistor having a shorter channel has a larger a width to lengthratio, the thin-film transistor can provide a larger switching current.As shown in FIG. 1, which is a structure of a conventional metal oxidethin-film transistor, in the manufacturing method for the conventionalmetal oxide thin-film transistor, a channel length L of the thin-filmtransistor is directly limited by a photolithography process such thatit is more difficult to realize a shorter channel.

SUMMARY OF THE INVENTION

In order to overcome the drawbacks of the conventional art, the purposeof the present invention is to provide a new metal oxide thin-filmtransistor and manufacturing method for the same, which can solve theshort channel problem of the thin-film transistor of the conventionalart in order to increase the performance of the thin-film transistor.

The present invention includes two aspects, in one aspect, the presentinvention provides a metal oxide thin-film transistor, comprising: asubstrate; a source electrode, a barrier layer and a drain electrodewhich are sequentially formed on the substrate; and a semiconductoractive layer formed on side surfaces of the source electrode and thedrain electrode; wherein, the semiconductor active layer is respectivelyconnected with the source electrode and the drain electrode.

(For the source and the drain electrode 1) in a cross-sectionalstructure of the metal oxide thin-film transistor, each of the sourceelectrode, the barrier layer and the drain electrode is a trapezoidalstructure that a length of an upper surface is less than a length of alower surface; a length of a lower surface of the barrier layer is thesame as a length of an upper surface of the source electrode, and alength of a lower surface of the drain electrode is the same as a lengthof an upper surface of the barrier layer.

(For the source and the drain electrode 2) each of the source electrode,the barrier layer and the drain electrode is a trapezoidal structurethat a length of an upper surface is less than a length of a lowersurface; a length of a lower surface of the barrier layer is the same asa length of an upper surface of the source electrode, the drainelectrode is formed on left and right sides of an upper surface of thebarrier layer, and the drain electrode located at the left side of thebarrier layer and the drain electrode located at the right side of thebarrier layer are connected with each other.

(For the source and the drain electrode 3) in a cross-sectionalstructure of the metal oxide thin-film transistor, each of the sourceelectrode, the barrier layer and the drain electrode is a trapezoidalstructure that a length of an upper surface is less than a length of alower surface; a length of a lower surface of the drain electrode is thesame as a length of an upper surface of the barrier layer, a length of alower surface of the barrier layer is less than a length of an uppersurface of the source electrode such that a portion of the sourceelectrode is exposed outside a covering range of the barrier layer.

Furthermore, a left side and a right side of the source electrode arerespectively protruded from the barrier layer and the drain electrode,and are exposed outside a covering range of the barrier layer.

(The semiconductor layer-patterning) furthermore, the semiconductoractive layer is a patterned semiconductor active layer, the patternedsemiconductor active layer includes a first patterned semiconductoractive layer located at and simultaneously contacted with a left side ofthe drain electrode and a left side of the source electrode, and asecond patterned semiconductor active layer located at andsimultaneously contacted with a right side of the drain electrode and aright side of the source electrode.

(The barrier layer) Optionally, the barrier layer is an insulation layeror a semiconductor barrier layer.

Optionally, the material of the insulation layer selects one or acombination of SiNx and SiOx.

Optionally, the material of the semiconductor barrier layer selects fromone or a combination of a ZnO based, a SnO₂ based and an In₂O₃ basedmaterials. It can be understood that the semiconductor barrier layer isa semiconductor layer with a high resistance.

(Further provided with GI) furthermore, a gate insulation layer isformed on the semiconductor active layer.

(A gate electrode is further provided) Furthermore, a gate electrode isformed on the gate insulation layer.

Furthermore, the gate electrode is a patterned gate electrode.

Furthermore, the patterned gate electrode is respectively located atleft and right sides of the gate insulation layer, the patterned gateelectrode located at the left side of the gate insulation layer is alsocorrespondingly disposed above the first patterned semiconductor activelayer, the patterned gate electrode located at the right side of thegate insulation layer is also correspondingly disposed above the secondpatterned semiconductor active layer, and the patterned gate electrodelocated at the left side and the patterned gate electrode located at theright side are connected with each other.

(A PV is further provided) furthermore, a passivation layer is formed onthe patterned gate electrode.

Optionally, the material of the drain electrode selects one or acomposite material of Al, Mo, Cu and Ag.

Optionally, the material of the source electrode selects one or acomposite material of Al, Mo, Cu and Ag.

Optionally, the semiconductor active layer selects one or a combinationof a ZnO based, an In₂O₃ based and a SnO₂ based material.

Optionally, the gate insulation layer selects one or a combination ofSiNx and SiOx.

Optionally, the material of the gate electrode selects one or acomposite material of Al, Mo, Cu and Ag.

Optionally, the passivation layer selects one or a combination of SiNxand SiOx.

In a second aspect, the present invention also provides a manufacturingmethod for the metal oxide thin-film transistor described above,comprising steps of:

preparing a substrate;

sequentially forming a source electrode, a barrier layer and a drainelectrode on the substrate;

forming a semiconductor active layer on side surfaces of the sourceelectrode and the drain electrode such that the semiconductor activelayer is respectively connected with the source electrode and the drainelectrode.

a substrate;

a source electrode, a barrier layer and a drain electrode which aresequentially formed on the substrate; and

a semiconductor active layer formed on side surfaces of the sourceelectrode and the drain electrode;

wherein, the semiconductor active layer is respectively connected withthe source electrode and the drain electrode.

(The source and drain electrode-specifically) furthermore, the step ofsequentially forming a source electrode, a barrier layer and a drainelectrode on the substrate comprises forming a first metal layer on thesubstrate, forming a barrier layer on the first metal layer, forming asecond metal layer on the barrier layer, performing a photolithographyprocess to the second metal layer, the barrier layer and the first metallayer such that the first metal layer forms the source electrode and thesecond metal layer forms the drain electrode.

(Halftone or grayscale mask) furthermore, the step of performing aphotolithography process to the second metal layer, the barrier layerand the first metal layer comprises adopting a half-tone mask and/or agrayscale mask to coating a photoresist; after exposing and developing,forming a photolithography pattern; and after etching and stripping thephotoresist, forming the source electrode and the drain electrode.

(For the source and the drain electrode 1) in a cross-sectionalstructure of the metal oxide thin-film transistor, each of the sourceelectrode, the barrier layer and the drain electrode is a trapezoidalstructure that a length of an upper surface is less than a length of alower surface; a length of a lower surface of the barrier layer is thesame as a length of an upper surface of the source electrode, and alength of a lower surface of the drain electrode is the same as a lengthof an upper surface of the barrier layer.

(For the source and the drain electrode 2) each of the source electrode,the barrier layer and the drain electrode is a trapezoidal structurethat a length of an upper surface is less than a length of a lowersurface; a length of a lower surface of the barrier layer is the same asa length of an upper surface of the source electrode, the drainelectrode is formed on left and right sides of an upper surface of thebarrier layer, and the drain electrode located at the left side of thebarrier layer and the drain electrode located at the right side of thebarrier layer are connected with each other.

(For the source and the drain electrode 3) in a cross-sectionalstructure of the metal oxide thin-film transistor, each of the sourceelectrode, the barrier layer and the drain electrode is a trapezoidalstructure that a length of an upper surface is less than a length of alower surface; a length of a lower surface of the drain electrode is thesame as a length of an upper surface of the barrier layer, a length of alower surface of the barrier layer is less than a length of an uppersurface of the source electrode such that a portion of the sourceelectrode is exposed outside a covering range of the barrier layer.

Furthermore, a left side and a right side of the source electrode arerespectively protruded from the barrier layer and the drain electrode,and are exposed outside a covering range of the barrier layer.

(The semiconductor active layer-specifically) furthermore, the step offorming a semiconductor active layer on side surfaces of the sourceelectrode and the drain electrode comprises performing aphotolithography process to the semiconductor active layer in order toobtain a patterned semiconductor active layer, and the patternedsemiconductor active layer includes a first patterned semiconductoractive layer located at and simultaneously contacted with a left side ofthe drain electrode and a left side of the source electrode, and asecond patterned semiconductor active layer located at andsimultaneously contacted with a right side of the drain electrode and aright side of the source electrode.

(The barrier layer) Optionally, the barrier layer is an insulation layeror a semiconductor barrier layer.

Optionally, the material of the insulation layer selects one or acombination of SiNx and SiOx.

Optionally, the material of the semiconductor barrier layer selects fromone or a combination of a ZnO based, a SnO₂ based and an In₂O₃ basedmaterials. It can be understood that the semiconductor barrier layer isa semiconductor layer with a high resistance.

(The gate insulation layer) furthermore, the manufacturing method of thepresent invention further comprises a following step: forming a gateinsulation layer on the semiconductor active layer.

(The gate electrode) furthermore, the manufacturing method of thepresent invention further comprises a following step: forming a gateelectrode on the gate insulation layer.

(The gate electrode-specific photolithography) furthermore, the step offorming a gate electrode on the gate insulation layer is depositing athird metal layer, performing a photolithography process to the thirdmetal layer to obtain a patterned gate electrode.

(The gate electrode-specifically) Furthermore, the patterned gateelectrode is respectively located at left and right sides of the gateinsulation layer, the patterned gate electrode located at the left sideof the gate insulation layer is also correspondingly disposed above thefirst patterned semiconductor active layer, the patterned gate electrodelocated at the right side of the gate insulation layer is alsocorrespondingly disposed above the second patterned semiconductor activelayer, and the patterned gate electrode located at the left side and thepatterned gate electrode located at the right side are connected witheach other.

(The passivation layer) furthermore, the manufacturing method of thepresent invention further comprises a following step: forming apassivation layer on the patterned gate electrode.

(The material) Optionally, the material of the drain electrode selectsone or a composite material of Al, Mo, Cu and Ag.

Optionally, the material of the source electrode selects one or acomposite material of Al, Mo, Cu and Ag.

Optionally, the semiconductor active layer selects one or a combinationof a ZnO based, an In₂O₃ based and a SnO₂ based material.

Optionally, the gate insulation layer selects one or a combination ofSiNx and SiOx.

Optionally, the material of the gate electrode selects one or acomposite material of Al, Mo, Cu and Ag.

Optionally, the passivation layer selects one or a combination of SiNxand SiOx.

Compared with the prior art, the beneficial effects of the presentinvention are as follows:

In a conventional metal oxide thin-film transistor, generally,sequentially forming a gate electrode, a gate insulation layer and asemiconductor active layer, and a source electrode and a drain electrodeare respectively formed at two sides of the semiconductor active layer.However, in the above structure, a channel length of the thin-filmtransistor is limited by the precision of the photolithography process,which is hard to realize a shorter channel length. In the presentinvention, a new metal oxide thin-film transistor and manufacturing forthe same are provided. A source electrode and a drain electrode arefirstly formed on the substrate, and a barrier layer for separating theboth is disposed such that the source electrode, the drain electrode andthe barrier layer are in parallel to the substrate and the layers are inparallel to each other. Then a semiconductor active layer isrespectively formed at left and right sides of the drain electrode andthe source electrode as well. Then, a gate insulation layer and a gateelectrode are formed. That is, the source and drain electrodes are inparallel to the substrate, and the semiconductor active layer iscontacted with the source electrode and the drain electrode by avertical covering or a step covering way in order to obtain a thin-filmtransistor totally different from the conventional thin-film transistorthat the semiconductor active layer is in parallel with the substrate.

In the metal oxide thin-film transistor of the present invention, thechannel length does not directly depend on the photolithography process,but depends on a length of a side surface of the source electrode andthe drain electrode contacted with the semiconductor active layer.Because the structure is not limited by the complicated photolithographyprocess, a thin-film transistor having a shorter channel can bemanufactured in order to improve the device performance such as on-statecurrent of the thin-film transistor, which can meet the displayrequirement for a higher performance.

Besides, in the metal oxide thin-film transistor of the presentinvention, through increasing a length of the source electrode on thesubstrate, the source electrode can fully function as a light-shieldinglayer in order to decrease the affection of the device performance bythe backlight to the thin-film transistor, which can further increasethe performance of the thin-film transistor.

Finally, in the metal oxide thin-film transistor of the presentinvention, through designing the drain electrode to be respectivelylocated at two sides of the barrier layer and left and right sides ofdrain electrode are connected in a plane structure of the thin-filmtransistor. The advantage is that an overlap portion between the drainelectrode and the gate electrode can be reduced in order to decrease theparasitic capacitance, and increase the performance of the thin-filmtransistor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a metal oxide thin-film transistor ofthe conventional art;

FIG. 2A to FIG. 2F are flow charts of the manufacturing method for themetal oxide thin-film transistor of a first embodiment of the presentinvention;

FIG. 2G is a perspective view of a plane structure of a metal oxidethin-film transistor of first embodiment of the present invention;

FIG. 3 is a schematic diagram of a cross-sectional structure of a metaloxide thin-film transistor of first embodiment of the present invention;

FIG. 4A is a schematic diagram of a cross-sectional structure of a metaloxide thin-film transistor of a second embodiment of the presentinvention;

FIG. 4B is a perspective view of a plane structure of a metal oxidethin-film transistor of the second embodiment of the present invention;and

FIG. 5 is a schematic diagram of a cross-sectional structure of a metaloxide thin-film transistor of a third embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT First Embodiment

The present embodiment provides a manufacturing method for a metal oxidethin-film transistor, comprising following steps:

As shown in FIG. 2A, preparing a substrate 1, and through a sputteringmethod to sequentially deposit a first metal layer 21, a barrier layer22 and a second metal layer 23. Wherein, each of the first metal layerand the second metal layer adopts metal molybdenum (Mo), and the barrierlayer adopts a SiOx material. In the present embodiment, the barrierlayer can be an insulation layer, or a semiconductor layer having ahigher resistance, that is, a semiconductor layer with high resistance.When the barrier layer is an insulation layer, a SiNx material can alsobe adopted. When the barrier layer is a semiconductor layer with highresistance, a ZnO based, a SnO₂ based or an In₂O₃ based transparentoxide semiconductor material can be adopted. Each of the first metallayer and the second metal layer can also adopt other metal materialssuch as metal materials of Al, Cu and Ag.

As shown in FIG. 2B, performing a photolithography process to the firstmetal layer, the barrier layer and the second metal layer. Specifically,coating a photoresist (not shown) on the second metal layer 23, using ahalf-tone mask for exposing, developing such that the first metal layer21, the barrier layer 22 and the second metal layer 23 formphotolithography patterns. Then, etching the first metal layer, thebarrier layer and the second metal layer outside a protection range ofthe photoresist, and stripping the photoresist such that the first metallayer forms a source electrode 24, the second metal layer forms a drainelectrode 25. In the present embodiment, from a cross-sectionalstructure of the metal oxide thin-film transistor (that is the structureshown in FIG. 2B). After photolithography, film layers which are inparallel to the substrate 1: the source electrode 24, the barrier layer22 and the drain electrode 25 are formed. In the present embodiment, thesource electrode 24, the barrier layer 22 and the drain electrode 25 areall continuous and complete film layers. Lengths of the film layers aregradually decreased from a lower surface to an upper surface such thatin the cross-sectional structure of the metal oxide thin-filmtransistor, the source electrode 24, the barrier layer 22 and the drainelectrode 25 form a trapezoid which is short at top and long at bottom.Wherein, a lower surface of the barrier layer 22 just covers an uppersurface of the source electrode 24, a lower surface of the drainelectrode 25 just covers an upper surface of the barrier layer 22. Itcan be understood that in the manufacturing method of the presentembodiment, a grayscale mask can be adopted for exposing the first metallayer, the barrier layer and the second metal layer so that finally, asource electrode and a drain electrode having photolithography patternscan be obtained.

As shown in FIG. 2C, using a sputtering method to deposit a ZnO basedmaterial on surfaces of the substrate 1, the source electrode 24, thebarrier layer 22 and the drain electrode 25 which are exposed outside asa semiconductor active layer, and performing a photolithography process.Specifically, coating a photoresist on the semiconductor active layer,exposing and developing in order to form a photolithography pattern.Then, etching and stripping the photoresist in order to form a patternedsemiconductor active layer 3. The patterned semiconductor active layer 3includes a first patterned semiconductor active layer 31 located at andsimultaneously contacted with a left side of the drain electrode 25 anda left side of the source electrode 24, and a second patternedsemiconductor active layer 32 located at and simultaneously contactedwith a right side of the drain electrode 25 and a right side of thesource electrode 24. Besides, the patterned semiconductor active layer 3is respectively contacted with a left side and a right side of thebarrier layer 22. It can be understood that the semiconductor activelayer can also adopt a SnO₂ based or an In₂O₃ based transparent oxidesemiconductor material.

In the present embodiment, from a cross-sectional structure of the metaloxide thin-film transistor (that is the structure shown in FIG. 2C) thepatterned semiconductor active layer is contacted with the sourceelectrode and the drain electrode respectively at left and right sidesof the source electrode and the drain electrode. Therefore, the channelis formed at left and right sides of the source electrode and the drainelectrode. That is, the channel length of the thin-film transistor ofthe present embodiment depends on lengths at left and right sides of thesource electrode and drain electrode, which is not limited by thecondition of the photolithography process anymore. Accordingly, thethin-film transistor of the present embodiment can realize a shortchannel structure.

As shown in FIG. 2D, using a sputtering method to deposit SiOx as a gateinsulation layer 4 on surfaces of the substrate 1, the patternedsemiconductor active layer 3 and the drain electrode 25 which areexposed outside. The gate insulation layer can also adopt an insulationmaterial of SiNx or Al₂O₃.

As shown in FIG. 2E, using a sputtering method to deposit metalmolybdenum (Mo) on the gate insulation layer 4 as a third metal layer,and performing a photolithography process to the third metal layer.Specifically, coating a photoresist on the third metal layer, exposingand developing to form a photolithography pattern. Then, etching andstripping the photoresist to form a patterned gate electrode 5. From across-sectional structure of the metal oxide thin-film transistor (thatis the structure shown in FIG. 2E), the gate electrode 5 arerespectively located at left and right sides of the gate insulationlayer 4. However, as shown in FIG. 2G, from a perspective view of aplane structure of the metal oxide thin-film transistor, the gateelectrode located at a left side is connected with the gate electrodelocated at a right side in the plane structure of the metal oxidethin-film transistor. It can be understood that, in order to clearlyshow the connection property of the gate electrode in the planestructure of the metal oxide thin-film transistor, in FIG. 2G, onlypartial main structures of the metal oxide thin-film transistor areshown, including the source electrode, the drain electrode, the barrierlayer, the patterned semiconductor active layer and the gate electrode.

As shown in FIG. 2F, through a sputtering method to deposit SiNx onsurfaces of the gate insulation layer 4 and the gate electrode 5 whichare exposed outside as a passivation layer 6.

It can be understood that the manufacturing method of the presentembodiment for depositing the first metal layer, the second metal layer,the third metal layer and the semiconductor active layer can also adoptone of the evaporation and sol-gel method. The manufacturing method ofthe present embodiment for depositing the gate insulation layer, thepassivation layer and the barrier layer can also adopt a chemical vapordeposition.

The present embodiment further provides a metal oxide thin-filmtransistor manufactured by the above method, as shown in FIG. 3, themetal oxide thin-film transistor includes a substrate 1; a sourceelectrode 24, a barrier layer 22 and a drain electrode 25 which aresequentially formed on the substrate 1; a patterned semiconductor activelayer 3 respectively formed on left and right sides of the sourceelectrode 24 and the drain electrode 25; a gate insulation layer 4formed on surfaces of the substrate 1, the patterned semiconductoractive layer 3, the drain electrode 25 which are exposed outside; and agate electrode 5 formed at left and right sides of the gate insulationlayer 4, wherein the gate electrode located at left side and the gateelectrode located at right side are connected in a plane structure ofthe metal oxide thin-film transistor. In the present embodiment, thesource electrode and the drain electrode are both disposed on thesubstrate in parallel to a plane structure of the substrate. Thepatterned semiconductor active layer is disposed at left and right sidesof the source electrode and drain electrode in a vertical covering or astep covering way. That is, side lengths of the source electrode and thedrain electrode decide a channel length of the thin-film transistor. Theabove structure is not limited by the photolithography process, andbelongs to a new metal oxide thin-film transistor, which can realize ashort channel structure of the metal oxide thin-film transistor.

In the present embodiment, the material adopted by each film layer ofthe metal oxide thin-film transistor is the material described in theabove manufacturing method, no more repeating here.

Second Embodiment

The difference between the present embodiment and the first embodimentis that, as shown in FIG. 4A, after performing a photolithographyprocess to the first metal layer, the barrier layer and the second metallayer, from a cross-sectional structure of the metal oxide thin-filmtransistor, the drain electrode 25 after photolithography process arerespectively located at left and right sides of an upper surface of thebarrier layer 22 such that a middle portion of the upper surface of thebarrier layer 22 is exposed. At the same time, as shown in FIG. 4B, froma top view of a plane structure of the metal oxide thin-film transistor,the drain electrode located at a left side and the drain electrodelocated at a right side are connected. It can be understood that, inorder to clearly show the connection property of the drain electrode inthe plane structure of the metal oxide thin-film transistor, in FIG. 4B,only partial main structures of the metal oxide thin-film transistor areshown, including the source electrode, the drain electrode, the barrierlayer, the patterned semiconductor active layer and the gate electrode.

The metal oxide thin-film transistor obtained by the manufacturingmethod of the present embodiment, although from the plane structure ofthe metal oxide thin-film transistor, the drain electrode is acontinuous structure, however, from a cross-sectional structure of themetal oxide thin-film transistor, the drain electrode are respectivelylocated at left side and right side of the upper surface of the barrierlayer. The above structure can make an overlap portion between the gateelectrode and the drain electrode to be reduced in order to reduce theparasitic capacitance and increase the performance of the thin-filmtransistor.

Third Embodiment

The difference between the present embodiment and the manufacturingmethod in the first embodiment is that, when performing aphotolithography process to the first metal layer, the barrier layer andthe second metal layer, a grayscale mask is adopted for exposing anddeveloping. Finally, as shown in FIG. 5, from a cross-sectionalstructure of the metal oxide thin-film transistor, a lower surface ofthe barrier layer 22 only covers a portion of the source electrode,after the photolithography process, a length of an upper surface of thesource electrode 24 is greater than a length of a lower surface of thebarrier layer 22. That is, a left side and a right side of the sourceelectrode 24 are respectively protruded from the barrier layer 22 andthe drain electrode 25, and are exposed outside a covering range of thebarrier layer 22 and the drain electrode 25.

The metal oxide thin-film transistor obtained by the manufacturingmethod of the present embodiment, from the cross-sectional structure ofthe metal oxide thin-film transistor, because the length of the sourceelectrode on the substrate is increased, the source electrode can befully used as a light-shielding layer in order to reduce the affectionof the backlight to the property of the thin-film transistor so as tofurther increase the performance of the thin-film transistor.

The above description only illustrates the main structure of the metaloxide thin-film transistor, and the metal oxide thin-film transistor canalso include other normal functional structures, no more repeating here.

The above embodiment does not constitute a limitation of the scope ofprotection of the present technology solution. The person skilled in theart can understand: without exceeding the principle and spirit of thepresent invention, the above embodiments can be improved. Anymodifications, equivalent replacements and improvements based on thespirit and principles of the above embodiments should also be includedin the protection scope of the present technology solution.

What is claimed is:
 1. A metal oxide thin-film transistor, comprising: asubstrate; a source electrode, a barrier layer and a drain electrodewhich are sequentially formed on the substrate; and a semiconductoractive layer formed on side surfaces of the source electrode and thedrain electrode; wherein, the semiconductor active layer is respectivelyconnected with the source electrode and the drain electrode; andwherein, each of the source electrode, the barrier layer and the drainelectrode is a trapezoidal structure that a length of an upper surfaceis less than a length of a lower surface; a length of a lower surface ofthe barrier layer is the same as a length of an upper surface of thesource electrode, the drain electrode is formed on left and right sidesof an upper surface of the barrier layer, and the drain electrodelocated at the left side of the barrier layer and the drain electrodelocated at the right side of the barrier layer are connected with eachother.
 2. The metal oxide thin-film transistor according to claim 1,wherein, the semiconductor active layer is a patterned semiconductoractive layer, the patterned semiconductor active layer includes a firstpatterned semiconductor active layer located at and simultaneouslycontacted with a left side of the drain electrode and a left side of thesource electrode, and a second patterned semiconductor active layerlocated at and simultaneously contacted with a right side of the drainelectrode and a right side of the source electrode.
 3. The metal oxidethin-film transistor according to claim 2, wherein, a gate insulationlayer is formed on the semiconductor active layer, a patterned gateelectrode is formed on the gate insulation layer, the patterned gateelectrode is respectively located at left and right sides of the gateinsulation layer, the patterned gate electrode located at the left sideof the gate insulation layer is also correspondingly disposed above thefirst patterned semiconductor active layer, the patterned gate electrodelocated at the right side of the gate insulation layer is alsocorrespondingly disposed above the second patterned semiconductor activelayer, and the patterned gate electrode located at the left side and thepatterned gate electrode located at the right side are connected witheach other.
 4. A metal oxide thin-film transistor, comprising: asubstrate; a source electrode, a barrier layer and a drain electrodewhich are sequentially formed on the substrate; and a semiconductoractive layer formed on side surfaces of the source electrode and thedrain electrode; wherein, the semiconductor active layer is respectivelyconnected with the source electrode and the drain electrode; andwherein, the semiconductor active layer is a patterned semiconductoractive layer, the patterned semiconductor active layer includes a firstpatterned semiconductor active layer located at and simultaneouslycontacted with a left side of the drain electrode and a left side of thesource electrode, and a second patterned semiconductor active layerlocated at and simultaneously contacted with a right side of the drainelectrode and a right side of the source electrode.
 5. The metal oxidethin-film transistor according to claim 4, wherein, a gate insulationlayer is formed on the semiconductor active layer, a patterned gateelectrode is formed on the gate insulation layer, the patterned gateelectrode is respectively located at left and right sides of the gateinsulation layer, the patterned gate electrode located at the left sideof the gate insulation layer is also correspondingly disposed above thefirst patterned semiconductor active layer, the patterned gate electrodelocated at the right side of the gate insulation layer is alsocorrespondingly disposed above the second patterned semiconductor activelayer, and the patterned gate electrode located at the left side and thepatterned gate electrode located at the right side are connected witheach other.